In this project, we are going to investigate peak to average power ratio (PAPR) reductiontechniques for OFDM-based wireless communication systems under carrier aggregationstructures, such as in 4G and 5G systems. First, we would like to utilize signal processingtechniques to deal with the PAPR problems. We are interesting in reducing PAPR by using optimaliterative clipping and filtering (OICF) methods. The advantage of clipping and filteringis easy to work that is compared with other techniques. The OICF method can greatly reducethe number of iterations and minimize the error vector magnitude (EVM), but the complexityand the computational cost are high. We consider the reduction of the computational costfor the OICF-based method. We will also investigate the PAPR reduction techniques for theuse in 4G/5G along with the carrier aggregation technique.Besides, we would like to consider waveform designs. We are interested in the parameterselection by using our previous proposed k-exponential pulse shaping filters. Thek-exponential filter has a single mathematical expression which is flexible and simpler inthe design. It can also provide better PAPR reduction. Therefore, in this work, we investigatethe application of the filter to the new OFDM-based wireless systems. An improved versionof the waveform may be derived in the project. The performance in the receiver end wouldbe evaluated for both the signal processing approach and the waveform design.